Process of preparing lubricant-impregnated fibers

ABSTRACT

Fibers such as caustic treated non round polyester fibers are prepared having certain lubricants strongly adhered to the surfaces thereof. These fibers are prepared by contacting the fibers, such as immediately prior to a crimping device, with a suitable heated hydrophilic lubricant in a processing operation followed by heating to dry or the lubricant onto and/or into the surface of the fibers.

FIELD OF THE INVENTION

This application is a continuation in part application of copendingapplication Ser. No. 07/466,849, now abandoned, filed Jan. 18,1990.

This invention relates to the preparation of fibers having lubricantimpregnated surfaces which have improved properties related to overallperformance including fiber opening, cohesion, processability and liquidtransport. This invention also relates to novel fiber lubricants.

BACKGROUND OF THE INVENTION

Fibers for nonwoven or textile materials must have certaincharacteristics in order to be considered useful or desirable. Importantperformance characteristics to consider in selecting a fiber or fibersfor a wide range of nonwoven, knitted and woven products include thefollowing: (1) fiber processability on nonwoven and textile equipment(efficiency, cost effectiveness); (2) fiber/fabric/material "hand" andoverall aesthetics when viewed, touched, used or worn (abrasiveness,softness, fiber covering power, opacity, comfort, drape, appearance,perception of suitability); (3) strength; (4) abrasion resistance; and(5) when applicable, liquid transport characteristics (wetting, wicking,absorption, liquid transport durability).

Nonwoven materials are manufactured by means other than weaving andknitting. The terms "nonwoven" and "nonwoven fabric" are generaldescriptive terms for a broad range of products, such as absorbent pads,wiping/cleaning webs or fabrics, insulation, aroma/flavor materials,liners, wicks, relatively thick battings, compressed bonded battings orwebs, bandages, incontinence structures, filters and many otherproducts. Interest in nonwoven materials is enhanced by the fact thatsuch materials can be mass produced efficiently and at relatively lowcost to satisfy many important consumer and industrial needs.Improvements in man made fibers have contributed to the development ofthe nonwoven industry.

Man-made materials have become increasingly plentiful and inexpensive.However, in certain characteristics many of these materials do notcompare well to natural fibers such as in the ability to transportmoisture satisfactorily. Several methods have been devised to improvethe characteristics of man made materials, such as polyester, to moreclosely resemble natural fiber, such as cotton. U.S. Pat. Nos.2,590,402, 2,781,242, 2,828,528 and 4,008,044 and the Journal of AppliedPolymer Science, Vol. 33, Page 455 (1987) all disclose the treatment ofcertain polyester fabrics with caustic to improve certain propertiessuch as handle and softness. U.S. Pat. No. 4,374,960 discloses theproduction of polyester fibers of improved stability that are made bymixing the polyester and an end capping reagent prior to fiberformation. EP 0,188,091 discloses the production of a highly absorbentnonwoven web by coating the web with super absorbent polymericparticles. U.S. Pat. No. 4,842,792 discloses fibers of improved cover,softness and wetting characteristics that are produced by caustictreatment of various polyesters which have continuous grooves in thecross-section. It is disclosed in the Journal Of Applied polymerScience, Vol. 25, PP1737-1744 (1980) that a fabric of increased dyeuptake can be made using a concentrated non ionic surfactant (TRITONX-100 made by Rohm and Haas Corp.) at a temperature between 180° and220° C. for five minutes. Removal of excess liquid from fibers isdisclosed in U.S. Pat. Nos. 3,458,890 and 3,786,574. Measurement ofcohesion of crimped staple fiber is disclosed in U.S. Pat. No.4,649,605.

All of these various aforementioned characteristics are important;however, unlike fabrics, staple fibers must also be satisfactorilyprocessable in an economical manner under conventional productionconditions by the equipment used in nonwoven and textile manufacture.Staple fibers are cut into suitable lengths (usually about 1 to 10 cm)for processing in a manner similar to natural staple fibers, such ascotton, in both textile and nonwoven machinery. These fibers mustperform satisfactorily in such known operations as opening, blending,feeding, carding, bonding, heating, compressing, cooling,hydro-entangling, needle-punching, drawing, roving, spinning, knitting,weaving, and others as selected for the various nonwoven or textilematerials.

Crimping of staple fiber by various means has been found to be anessential element in producing a certain controlled amount of fibercohesion or resistance to pulling apart in forming carded webs. Thesewebs of "opened" (separated) fibers are formed in flat top or roller topcarding machines or the like as part of nonwoven or textile processes.

Poor crimp formation, especially in fibers with non roundcross-sections, has been associated with low and variable cohesion, weakwebs, web separation, and poor processability during carding and/orsubsequent operations. Relatively high lubricant levels (applied at roomtemperature), particularly above about 0.2 weight percent, of certainprocessing lubricants can cause unsatisfactory cohesion andprocessability problems in carding, etc. When such high levels of theselubricants are applied prior to the crimper (such as by conventionalkiss rolls), low fiber-to-metal friction within the crimping chamberinterferes with the capability to produce normal crimp frequency (crimpsper inch) with sufficiently low (narrow) average crimp angle andrelatively "V-shaped" crimp apex. Poor crimp is characterized bycomparatively low and/or excessively variable crimp frequency and/orwide (open) average crimp angle; and/or comparatively "U-shaped" crimpapex.

Two types of commonly used processing lubricants are based on potassiumlauryl phosphate or mineral oil with the addition of antistatic agents,friction modifiers, etc. as needed. At high levels (above 0.2 to 2 wt. %or greater) these and many other lubricants applied prior to the crimperusing prior-art methods (usually lubricant-coated, rotating, contactrolls at approximately room temperature located remote from the crimperinput) can have an adverse effect on crimp formation and/or tend tocause problems in carding by poor cohesion and/or by building uprelatively quickly a detrimental coating on the carding wire and/orother problems. Additionally, these lubricants do not have goodhydrophilic action.

Additionally, for certain applications, liquid-transport durability is adesirable characteristic but difficult to obtain in some man madefibers. Certain man made fibers, particularly those with suitablenon-round cross-sections, have some initial liquid-transportcharacteristics. However, after wet usage, washing or scouring, theability of these fibers to transport liquid can in some instancesdiminish significantly.

Any method of improving any of the aforementioned characteristicswithout significant adverse affects on other characteristics would bevery desirable.

SUMMARY OF THE INVENTION

The present invention is directed to fibers having improved openingcharacteristics, cohesion, processability, hand, and/or liquid transportproperties in which a significant amount of a lubricant is adhered tothe surfaces of the fibers.

These improved fibers are made by the process comprising spreading at anelevated temperature onto the fibers a substantially non-tacky wettablelubricant as a mixture, emulsion or solution in water, followed by apressure application means and subsequently heating the fibers at anelevated temperature for time sufficient to dry or bake the lubricantonto or into the surface of the fibers. Fibers made by this process areparticularly useful in making nonwoven materials.

Another aspect of this invention entails novel fiber processinglubricants comprising a mixture of high and low molecular weightpolyethylene glycol fatty acid esters preferably in combination with aminor amount of a suitable antistatic agent. In some applications, thisnovel lubricant or mixture can be applied to the fibers of choice atabout room temperature by various means as a less preferred option.

Yet another aspect of this invention entails a novel hydrophilicprocessing lubricant for use with fibers, particularly binder fibers,comprising a mixture of a suitable antistatic agent and at least onepolyethylene glycol monolaurate or monostearate having a sorbitan groupsuch as polyethylene glycol 880 sorbitan monolaurate and/or polyethyleneglycol 880 sorbitan monostearate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1--Schematic flow chart of a preferred tow-processing operationwithin the scope of the present invention. The solution of heatedprocessing lubricant is preferably applied by at least one jetimmediately prior to the crimper. At least one component of a lubricantand/or a cross linking agent can be applied prior to the heat settingunit.

FIG. 2--Schematic representation of examples of fiber cross-sections ofpreferred non round spun fibers having a plurality of grooves. FIG. 2ais a representation of a more preferred cross-section with two groovesand is particularly useful for deniers less than about 5.0. L1 is amajor axis; L2 is a minor axis, W is the width of the groove; thickerlines represent the surfaces of the grooves; and the thinner linesrepresent the surfaces outside the grooves. FIG. 2b illustrates across-section which has four grooves. FIG. 2c illustrates variouscross-sections which have continuous grooves. FIG. 2d represents thegeneral form of a much preferred eight-groove cross-section which isuseful for deniers greater than about 5.

FIG. 3--Graph of the wettability (vertical-wicking performance) ofSamples A, B, C. and D from Example 5. This graph illustrates the amountof water in grams transported over time in seconds.

FIG. 4--Detail of a most preferred method of applying the hot solutionof processing lubricant to the fibers of a tow prior to crimping. Thecrimper is a stuffer box type crimper with advancing rollers or can beany suitable type of crimper.

FIG. 5--Graph representing the drop wetting time in seconds of variousnonwoven fabrics made from the various fiber samples as described inExample 2.

FIG. 6--Schematic flow chart of a most preferred tow processingoperation within the scope of the present invention. Excess liquid isremoved by at least a Partial Liquid Removal Means 1 following both thedrafting bath and the neutralization bath and the tow is sufficientlydried prior to being contacted by the heated solution of processinglubricant at 2B immediately prior to crimping. Additional or alternateprocessing-lubricant application means, treatment, and/or neutralizationmeans are illustrated at 2A. If an additional means is utilized at 2A,then the tow is substantially dried prior to being contacted by theheated solution of processing lubricant at 2B. Squeeze rolls are shownat the input to the 4th set of rolls.

DETAILED DESCRIPTION OF THE INVENTION

Fibers produced according to the process of the present invention,particularly those having at least one continuous groove, having eitherround or non-round cross-section, are characterized by an unexpectedcombination of desirable properties including fiber opening, card webquality, cohesiveness, good textile and nonwoven processability, hand,and bonding properties. In addition the liquid transport capabilitiesare at least as good as and in some instances possibly better than thoseof comparable fibers that are not treated according to the process ofthe present invention. The liquid transport capability is more durablein that, after vigorous scouring such as with hot water for many secondsas later described, these treated fibers and products made therefrom (atleast when caustic treated) unexpectedly (1) retain effective amounts ofcertain lubricants and (2) more importantly, provide greater liquidtransport durability than comparable non-treated fibers/products.

In particular, these novel fibers can be efficiently conducted throughnonwoven processes with subsequent bonding and/or calendering processes,as appropriate, to provide hydrophilic fabrics which have excellentcover, softness, hand and/or overall properties compared to untreatedfiber.

If desired, the process of the present invention also eliminates theneed for steam application prior to the crimper; however, steam heatingis a viable, yet less desirable, option for heating the novel lubricantmixture.

Any method of applying the processing lubricant to sufficiently coat thefibers, including the grooves, that also softens the fibers just priorto the crimper is envisioned to be within the scope of the presentinvention.

A preferred process of the present invention comprises:

(A) contacting at an elevated temperature at least one fiber with asufficient amount of a solution containing a sufficient amount of atleast one substantially non-tacky non-static hydrophilic (wettable)processing lubricant to coat said fiber;

(B) crimping at an elevated temperature the lubricant-coated fiber of(A); and

(C) heating the thus crimped lubricant-coated fiber of (B) at asufficient temperature for a sufficient time to dry or bake saidlubricant onto and/or into the surface of said fiber.

A more preferred process of the present invention comprises:

(A) coating at least one caustic treated non-round fiber with at leastabout 0.1 weight % and most preferably at least about 0.3 weight % of atleast one substantially non-tacky, wettable, processing lubricant withantistatic properties at a temperature between about 40° C. and theboiling point of the lubricant to coat said fiber;

(B) crimping at an elevated temperature the lubricant-coated fiber of(A); and

(C) heating the thus crimped lubricant coated fiber of (B) at atemperature between 40° and 180° C. for sufficient time to dry or bakethe lubricant onto and/or into the surface of said fiber.

The mixture, solution or emulsion of processing lubricant preferablycontains at least about 5 wt. % processing lubricant, more preferably atleast about 10 wt. % with about 20 wt. % being most preferred. Thesolution should be relatively free flowing in that when heated to atleast 40° C. it can spread and flow readily when it is placed on a glasssurface angled at 30° from horizontal. To avoid being too viscous thesolution preferably contains less than about 40 wt. % lubricant, morepreferably less than about 30 wt. %.

The resulting novel fibers are preferably coated with at least 0.1 wt. %lubricant based on the total wt. % of the fiber and lubricant and morepreferably at least about 0.2 wt. % lubricant with at least about 0.3 to3 wt. % lubricant being most preferred.

Not all lubricants are suitable for use in the present invention. Wehave found that commonly-used processing lubricants, such as potassiumlauryl phosphate and mineral oil types even applied according to theprocess of the present invention, at low and particularly high levels,are not suitable for use with liquid-transport fibers, particularly thecaustic-treated non-round fibers described hereinafter. It is believedthat the unsuitability of these lubricants is due to their relativehydrophobic nature. In addition, however, not all hydrophilic lubricantsare suitable. Suitable hydrophilic lubricants must also create at leasta certain minimum level of cohesion or fiber-to-fiber friction withoutbeing excessively "tacky" or "sticky" when dried as hereinafterdescribed.

The processing lubricant must be substantially non-tacky when dried. Inother words, when the lubricant is coated and dried on a surface, thatcoated surface should not easily adhere or "stick" to other non-tackysurfaces. The fibers coated with the dried on or baked-on non-tackylubricant should not be sticky and should be cardable and capable ofbeing efficiently separated (opened). These fibers should card withoutwrapping, or "loading" the main carding cylinder or other cardingcomponents and should produce carded webs which have sufficient strengthfor subsequent operations.

The processing lubricant should also act as a surfactant and be wettableor somewhat hydrophilic and mix with solutions, emulsions or mixturescontaining hot water although the processing lubricant could, ifdesired, be applied to fibers in a non-aqueous solution. When thislubricant is dried on a surface, such as a thin film of plastic, itshould spread or disperse water droplets that touch the surface. Thisprocessing lubricant should enhance the liquid-transport properties of afiber, once it is dried or baked onto and/or into the surface of thefiber.

Additionally, the processing lubricant should be of a substantially lowstatic nature and/or allow for at least satisfactory control of static.This lubricant should control static either alone or in the presence ofa minor amount of at least one antistatic agent.

Antistatic agents useful in the present invention include quaternaryamine salts, salts of polyoxyethylene inorganic fatty alcohol esters,ethosulfate salts of quaternary ammonium compounds, acid salts ofquaternary ammonium compounds, etc. The preferred antistatic agents arethe salts of quaternary ammonium compounds including the ethosulfatesalts and acid salts such as the acetates, lactates, and propionateswith the ethosulfate salts being more preferred. The most preferredethosulfate salt of a quaternary ammonium compound is 4-ethyl, 4-cetyl,morpholinium ethosulfate.

The processing lubricant of the present invention is preferably at leastpartially water soluble and is not too viscous when in solution withwater under the conditions when applied to the fibers. The lubricant ofthe present invention can contain a major portion of a polyoxyethylenefatty acid ester such as a methyl-capped polyoxyethylene laurate; apolyethylene glycol fatty acid ester such as a polyethylene glycollaurate; or a fatty acid glyceride such as a glyceryl oleate. Theprocessing lubricant of the present invention can also contain an amountof a compatible surfactant and/or softening agent. By compatible it ismeant that this component would not cause an adverse reaction such asgelling, coagulation, precipitation, etc.

The processing lubricant is preferably selected from (A) a mixture of amajor amount of a methyl-capped polyoxyethylene (x) fatty ester (xrepresents about 2 to 50 moles of ethylene oxide and the fatty estercontains 7 to 18 carbon atoms such as laurate), and a minor portion ofquaternary amine carbonate or other suitable antistatic agent; and (B) amixture of a major portion of at least one polyethylene glycol mono ordilaurate (molecular weight between about 80 and 2,000 with 400-600being more preferred) and, if needed, a minor amount of a suitableantistatic agent with the mixture (B) being the most preferredprocessing lubricant.

The mixture (A) preferably contains about 55 to 80% by wt. of amethyl-capped polyoxyethylene (x) laurate wherein x represents about 2to 50 moles of ethylene oxide.

According to another aspect of the present invention, an improvedlubricant mixture is provided that generally falls within (B) abovecontaining low and high molecular weight polyethylene glycol fatty acidesters such as polyethylene glycol 400 monolaurate and polyethyleneglycol 600 monolaurate plus a minor amount of a suitable antistaticagent, such as 4-ethyl, 4-cetyl, morpholinium ethosulfate. Bydefinition, a low molecular weight polyethylene glycol fatty acid esterhas a molecular weight in the polyethylene glycol portion below 500. Bydefinition, a high molecular weight polyethylene glycol fatty acid esterhas a molecular weight in the polyethylene glycol portion above 500. Themost preferred low molecular weight polyethylene glycol fatty acid esteris polyethylene glycol 400 monolaurate and the most preferred highmolecular weight polyethylene glycol fatty acid ester is polyethyleneglycol 600 monolaurate. This novel lubricant mixture is much preferredfor use in the present invention and preferably comprises a majorportion of substantially equal portions of the low molecular weightpolyethylene glycol fatty acid ester and the high molecular weightpolyethylene glycol fatty acid ester and a minor amount of a suitableantistatic agent, such as 4-ethyl, 4-cetyl, morpholinium ethosulfate.These components can be obtained from Henkel Corporation or ICI AmericasCorporation.

The novel lubricant mixture most preferably contains at least about 40weight percent of the low molecular weight polyethylene glycol fattyacid ester, at least about 40 weight percent of the high molecularweight polyethylene glycol fatty acid ester and about 20 to 1 weight %of a suitable antistatic agent with 4-ethyl, 4-cetyl, morpholiniumethosulfate being the preferred antistatic agent.

Other preferred lubricants, particularly for use with binder fibers,include a major portion of at least one polyethylene glycol monolaurateor monostearate having a sorbitan group such as polyethylene glycol 880sorbitan monolaurate and/or polyethylene glycol 880 sorbitanmonostearate mixed in water with a minor portion of a suitable antistat.This novel lubricant most preferably contains (excluding water) at leastabout 80 weight % polyethylene glycol 880 sorbitan monolaurate and/orpolyethylene glycol 880 sorbitan monostearate and about 1 to 20 weight %of a suitable antistat with 4-ethyl, 4-cetyl, morpholinium ethosulfatebeing most preferred.

A binder fiber is a material substantially in fiber form, such ascrimped staple which is blended as a minor component with a more stable,heat-resistant major component fiber, which can be heated and compressedto form a bonded nonwoven fabric.

The solution of lubricant can, if found to be appropriate for aparticular need, contain minor amounts of at least one other additive,such as a coloring agent, aroma-enhancing agent, scouring agent,anti-fungal or anti-bacterial agent, defoamer, additional antistaticagents, other hydrophilic components, a friction-modifying agent, asuper absorbent powder or polymer, fluorescent additive, antisepticadditive, additives suitable for cosmetic purposes, ethoxylated oleylalcohol (cosmetic grade, etc.). Such other additive can be applied, asan option, to the final nonwoven or textile product. As appropriate andfeasible, suitable components of our novel lubricants can be modified,such as by methyl capping, etc. The processing lubricant can, if appliedin a separate step, contain a cross linking agent with or without acatalyst and/or additives which have bonding properties. An example of asuitable cross linking agent is "LUREEN 2195" a hydrophobic crosslinking silicone from G. A. Goulston Co. Examples of suitablefriction-modifying agents are a polyoxyethylene-polyoxypropylenecondensate, such as PLURACOL V-10 and fatty acid (C10-C18)diethanolamide condensates, such as made by Emery Chemical Co.

The processing lubricant can also contain minor or trace amounts ofadditives useful in the processing of fibers such as spinning lubricant,polymer, chemicals useful in dyeing, etc. and mixtures thereof.

The processing-lubricant solution solvent is preferably selected fromthe group consisting of water, water containing a minor amount ofacetone, ethanol or other solvents, water containing minor amounts ofreaction products or materials washed from the fiber, etc. and mixturesthereof with plain or distilled water being more preferred.

Although the present invention is an improvement over the art, not alllubricants, including the novel lubricants, perform equally well on allfibers. The most preferred suitability must be determined on acase-by-case basis matching fiber and specific lubricant.

Additionally, the novel lubricants can be applied as appropriate toplastic tapes, ribbons, films and other manufactured articles.

Prior to the application of the lubricant the fibers of the presentinvention are preferably caustic treated, such as by a caustic solutionat an appropriate concentration followed by neutralization. This caustictreatment is most preferably conducted prior to application of the hotprocessing lubricant solution as shown in FIGS. 1 and 6. This caustictreatment is preferably conducted by the following steps: (1) caustictreating the fiber, (2) heating the fiber, and (3) substantiallyneutralizing excess caustic using a suitable acid solution (such asacetic or citric acid). This heating step is preferably conducted at atemperature of at least about 130° C., more preferably at a temperatureof at least about 145° C. for approximately 2 to about 25 seconds. Ofcourse, this temperature should not be so high as to melt the fiber ordegrade the lubricant. The suitable acid used in the neutralizing stepis preferably selected from the group consisting of acetic acid, citricacid, ascorbic acid, and/or mixtures thereof. The process of the presentinvention in combination with this caustic treatment or surfacehydrolysis results in novel fibers which have unexpectedly a superiorcombination of important characteristics including processability,liquid-transport, and/or overall performance compared to other fibersnot treated by caustic and an appropriate amount of the novel hotlubricant prior to crimping.

The present invention is most preferably directed to caustic-treated andneutralized fibers with suitable non-round cross-sections havinglongitudinal grooves that are substantially continuous in which asignificant amount of a hydrophilic processing lubricant is adhered tothe surfaces of the fibers and a significant amount remains after ahot-water treatment as described. These fibers have improved overallperformance including processability. However, the novel process of thisinvention can be used to improve the crimp formation, cohesion,processability and overall performance of fibers not treated withcaustic.

Fibers with many longitudinal or axial grooves tend to hold liquid, suchas neutralization solution, in the grooves and do not permit sufficientlubricant to enter. Therefore, it is important to remove this excessliquid prior to contacting the fibers with the heated processinglubricant so that the grooves are substantially devoid of liquid. Thiscan be accomplished by a partial or total liquid removal process inwhich at least one liquid removal means, such as bars, squeeze rollers,and/or air jets physically removes a significant portion of the liquid.For substantially total liquid removal this physical removal must befollowed by drying at elevated temperatures prior to the application ofthe heated processing lubricant. FIG. 1 illustrates the location ofLiquid-Removal Means 1 that can be employed following the 1st stagedrafting bath and/or after the optional neutralization bath to at leastpartially remove liquid from the tow.

The fiber is contacted with a continuous flow or semicontinuous pulsedflow of the solution of processing lubricant at an elevated temperature,preferably at a temperature of at least about 40° C. up to the boilingpoint of the solution. This temperature is more preferably between about50° and 100° C. with a temperature less than about 95° C. being mostpreferred. For drawn polyesters this most preferred temperature isbetween about 70° and 95° C. For binder fibers, such as copolyesters andundrawn polyesters, the preferred temperature is between about 40° and70° C.

The application of the hot processing lubricant solution can beconducted in any suitable manner so long as substantial loss of heat isavoided (such as by fine droplet formation) and a sufficient amount ofthe processing lubricant is coated on the surface of each of the fibers.That amount should preferably be sufficient to maintain satisfactorycrimp formation, cohesion and processability. A much preferred processof applying this hot lubricant solution is by the use of one or morejets positioned just prior to crimping such as shown in FIG. 4. Thisfigure illustrates the use of both top and bottom jets to facilitatepenetration of the hot lubricant into the center of the fiber bundle(tow). It is important that, as far as it is practical, hot lubricantcontacts each fiber so as to heat and soften each fiber. Therefore,during or after contacting of the fiber with the continuous flow ofprocessing lubricant, an elevated temperature is maintained as thelubricant is spread in a substantially uniformly manner onto the fiber.A subsequent crimping or compression means (such as a crimper orcompression roll) is the preferred method used to spread the lubricantand press it into the grooves of the fiber. Additionally, thoroughlycoating the fibers with the proper lubricant, such as the most preferredof mixture (B) (heated lubricant antistat), helps protect the fibersagainst damage during the crimping process.

It is also preferred to spread the lubricant onto the fiber to a certainextent during and/or immediately after application of the lubricantprior to any crimping means. The lubricant can be spread by anyconventional means but is preferably spread by a spreader bar,compression rolls, and/or a hot lubricant application jet in the shapeof a spreader bar as shown in FIG. 4. These spreading means are alsopreferably vibrated.

To avoid scuffing or other damage to the fiber, the fiber should notcontact a dry jet surface. When a jet contacts the fibers, the slot orjet holes are most preferably located in a curved contact surfaceoriented towards the advancing fiber as shown in FIG. 4 to minimize drycontact between the tow and the bar in order to prevent scuffing orotherwise damaging the fiber as far as practical. Thus, FIG. 4illustrates a novel and much preferred application means for hotlubricant, particularly where at least one spreader bar is suitablymounted and equipped with vibration means to facilitate fiber separationand lubricant penetration into the tow band to coat the fibers moreuniformly. As an option, the bottom jet or jets can be spaced from thetow and can apply heated lubricant at sufficient pressure to impingeupon the tow. Appropriate supply tank, stirring means, heating means,pumping means, reconstitution means, housing, drains and recirculationwould be provided.

The use of hot-lubricant jets in series prior to the crimper on the towprocessing line is illustrated in FIG. 4. The tow is maintained underappropriate tension between the last roll and the crimper and, as statedabove and illustrated in FIG. 4, the slotted jet is oriented to preventcontact of the tow with a "dry" (unlubricated) surface (such as metal orceramic) which could cause damage to the fiber (fused fibers, brokenfilaments, "skin backs", etc.). A series of small holes can besubstituted for the slot, if desired. The adjustable flanges hold thetow in proper position and cover the slot or holes at the tow edges asrequired for various tow widths. This bottom jet with either a slot orholes can be constructed with multiple lubricant-supply chambersoriented across the tow band. FIG. 4 illustrates the multi-jetapplication means which is a most preferred embodiment of the presentinvention. In order to provide for adjustment of the % lubricant appliedand/or lubricant concentration used for any given fiber type, facilitiescan be provided to permit each jet to be operated, adjusted ordisconnected independently from the others. In a most preferredembodiment, at least one of the two top jets has a common mount and/orsupport member with at least one of the spreader bars such that the topjet and bar can be pivoted or elevated by any suitable means to provideconvenient access to the tow path during start-up when the tow is placedin the crimper rolls. One embodiment of this common mount and/or supportmember is illustrated in FIG. 4 by the broken lines. The first(upstream) jet applies heated lubricant on top of the tow band. Thelubricant forms a surprisingly stable, small concentration (bead) at theinput side of the first spreader bar. This spreader bar spreads thelubricant from the first jet and causes penetration into the tow, thusincreasing the uniformity of lubricant application (a top jet similar indesign to the bottom jet could also be used to replace the top jetand/or spreader bar). Lubricant applied by the bottom jet is pushedupward into the tow by the rounded top portion of this jet. An optionalspreader bar (not shown) located beneath the tow can be locateddownstream from the bottom jet and can have a common mount and/orsupport member with the bottom jet. The last (downstream) top jet canapply additional lubricant which forms a small bead on top of the tow atthe crimper input to be forced into the tow by the crimper rolls. Thebottom jet can be operated in combination with one of the top jets. Thisnovel multi-jet lubrication means should be located as close to thecrimper input as is practical preferably within about 90 inches (about225 cm) most preferably within about 60 inches (about 150 cm) of thecrimper with the closest jet most preferably located less than about 24inches (60 cm) from the crimper. It is preferred that the distance fromthe first jet to the third should not exceed about 6 feet (180 cm).

Appropriate insulation can be used to help maintain the lubricant in aheated condition. In addition, the jet(s) can be designed with a novelcirculation system (not shown) such that only a portion of the lubricantexits the jet(s) and is being constantly applied to the tow while theremainder of the lubricant is returned to be reheated in the heatedsupply tank in a semi-closed loop. This recycling of lubricant shouldhelp keep the lubricant hot and also avoid plugging of the jet. Theheated supply tank can be equipped with automatic monitoring andcorrection systems for lubricant concentration, temperature sensors,insulation, etc. as needed to facilitate uniform application of heatedlubricant.

A less preferred embodiment is similar to FIG. 4 except a lubricantcoated, rotating, tow-contact roll which is partially immersed in a bathof heated lubricant is substituted for the bottom slotted jet. Thisembodiment is much less preferred because it is more complex, would tendto contaminate the lubricant and is more difficult to insulate.

A less preferred option is the application of the most preferredlubricant in the neutralization bath followed by a removal means forexcess liquid and a heating means prior to the crimper.

An even less preferred option is the application of the most preferrednovel lubricant mixture by conventional means followed by a steamchamber to heat the fiber and applied lubricant followed by crimping andheating in a tow dryer unless contact means, such as spreader bars orrolls, are included to increase the penetration of the lubricant intothe grooves of the fibers.

Another less preferred option, although an improvement over the art, isthe application of a most preferred novel lubricant after the crimperand tow dryer in the conventional manner. However, the opportunities toforce heated lubricant onto and into the grooves of the fibers; toenhance crimp formation; and to help protect the fiber surfaces duringpassage through the crimper are lost. It is believed that, if aconventional application of steam is used prior to crimping, the novellubricant composition even though applied by conventional means, can beused to facilitate, to a certain extent, the processability of the fiberthrough nonwoven or textile machinery and to make some improvement inoverall performance. Such conventional application means can includeimmersion baths, spray-application means (such as by airless jets orair-powered jets, etc.), application cylinders with slot(s) or holes,electrostatic sprays, dual kiss-rolls, dual brush applicators, etc., toapply the novel hydrophilic lubricant(s) to each side of a tow band.This novel lubricant composition most preferably comprises at leastabout 45 weight % polyethylene glycol 400 monolaurate, at least about 45weight % polyethylene glycol 600 monolaurate and up to 10 weight %4-ethyl, 4-cetyl, morpholinium ethosulfate.

According to the process of the present invention, the fibers containingthe coating of heated processing lubricant must be treated to a dryingstep such as heating in the tow dryer. This tow dryer should be equippedwith an air circulation system. This completes the attachment of theprocessing lubricant securely to the surface of the fibers, particularlyto the surface in the grooves of non-round fibers and more particularlycaustic-treated grooves. The overall heating or drying time ispreferably less than about 7 minutes and more preferably less than about4 minutes. This drying step is preferably conducted at a temperature ofat least about 40° C. more preferably between 50° C. and 135° C. for atleast about 20 seconds; even more preferably between 50° C. and 115° C.for at least 90 seconds with at least 180 seconds being most preferred.For acetate fibers and drawn polyester fibers this more preferredtemperature is between about 60° C. and 115° C. For binder fibers suchas copolyesters and undrawn polyesters this temperature is between about40° C. and 70° C. However, it is understood that changes in dryingtemperature may be required in order to meet different end uses. Whencaustic is not used or when appropriate for a particular product, theheat-set cabinet can be operated at or near room temperature, ifdesired, with essentially all of the tow drying treatment beingaccomplished in the tow dryer.

The thus heated, lubricant-coated fiber, when appropriate, also can beheated a second time. This second heating temperature is preferably atleast about 10° to 60° C. higher than the first tow dryer section. Thecontacting time for this second heating is at least about 5 seconds.This second heating is preferably conducted at a temperature of at least135° C. for at least about 5 seconds; preferably over 10 seconds withover 20 seconds being most preferred. This second heating or tow dryingstep can also be conducted at a temperature of at least 175° C. for atleast about 2 seconds. The heating conditions used should be appropriatefor the type of nonwoven or textile processing used and the performancecharacteristics required for the eventual product.

We believe that most all types of synthetic fibers could be benefited,to some extent, by being treated according to the process of the presentinvention. Examples of suitable fibers that can be treated according tothe present invention include those selected from the group consistingof polyesters including copolyesters, cellulose acetate, modacrylic,nylon, olefins, viscose rayon, polyphenylene sulfide, fibers made frombiodegradable materials, and suitable mixtures or blends thereof. Thepreferred fibers that can be treated according to the present inventionare polyesters, cellulose acetate, modacrylic, nylon, and viscose rayonwith polyesters and cellulose acetate being most preferred. Thepreferred polyesters including copolyesters are selected from relativelyoriented polyesters, relatively unoriented polyesters, polyestersmodified for basic dyeability, polyesters containing starch, polyesterscontaining cellulose acetate, polyesters containing cellulosepropionate, polyesters containing cellulose butyrate, polyesterscontaining modified starch (such as starch acetate) and aliphaticpolyesters blended with cellulose esters. In addition, polyesters whichhave been modified chemically or by a polymerized exterior coating canbe benefited by being treated according to the process of the presentinvention.

The cellulose acetate fibers useful in the present invention areprepared by melt-spinning or conventional solvent-spinning means usingacetone as a solvent. The cellulose acetate can contain additives whichfurther enhance hydrophilic action and/or other desired properties.

The polyester materials useful in the present invention are polyestersor copolyesters that are well known in the art and can be prepared usingstandard techniques, such as, by polymerizing dicarboxylic acids oresters thereof and glycols. The dicarboxylic acid compounds used in theproduction of polyesters and copolyesters are well known to thoseskilled in the art and illustratively include terephthalic acid,isophthalic acid, p,p'-diphenyldicarboxylic acid, p,p'dicarboxydiphenylethane, p,p'-dicarboxydiphenyl hexane, p,p'-dicarboxydiphenyl ether,p,p'-dicarboxyphenoxy ethane, the like, and the dialkylesters thereofthat contain from 1 to about 5 carbon atoms in the alkyl groups thereof.

Suitable aliphatic glycols for the production of polyesters andcopolyesters are the acyclic and alicyclic aliphatic glycols having from2 to 10 carbon atoms, especially those represented by the generalformula HO(CH₂)_(p) OH, wherein p is an integer having a value of from 2to about 10, such as ethylene glycol, trimethylene glycol,tetramethylene glycol, pentamethylene glycol, decamethylene glycol, andthe like.

Other known suitable aliphatic glycols include,1,4-cyclohexanedimethanol, 3-ethyl 1,5-pentanediol, 1,4-xylylene,glycol, 2,2,4,4-tetramethyl 1,3-cyclobutanediol, and the like. One canalso have present a hydroxylcarboxyl compound such as 4,-hydroxybenzoicacid, 4-hydroxyethoxybenzoic acid, or any of the other hydroxylcarboxylcompounds known as useful to those skilled in the art.

It is also known that mixtures of the above dicarboxylic acid compoundsor mixtures of the aliphatic glycols can be used and that a minor amountof the dicarboxylic acid component, generally up to about 10 molepercent, can be replaced by other acids or modifiers such as adipicacid, sebacic acid, or the esters thereof, or with modifiers that impartimproved dyeability or dyeability with basic dyes to the polymers. Inaddition one can also include pigments (such as blanc fixe),delusterants (such as TiO₂) or optical brighteners by the knownprocedures and in the known amounts.

The most preferred polymers for use in the present invention are (1)relatively unoriented and relatively oriented poly(ethyleneterephthalate) (PET); (2) copolyesters based on poly(ethyleneterephthalate), particularly those suitable for use as binder fibers,(3) poly(ethylene terephthalate) containing cellulosic additives and/ormodified starch, such as starch acetate, and (4) cellulose acetatefibers.

The fibers of the present invention are preferably non-round fibershaving at least one continuous groove such as those disclosed in U.S.Pat. No. 4,842,792, U.S. Pat. No. 4,954,398 and U.S. patent applicationSer. No. 07/333,651, the disclosures of which are incorporated in theirentirety herein by reference. The surface of the groove is mostpreferably rougher than the surface outside the groove. Examples ofvarious fiber cross sections are illustrated in FIGS. 2a, 2b, 2c and 2d.FIGS. 2a and 2d are the more preferred cross-sections treated accordingto the present invention. It is believed, however, that the overallperformance of any non-round fiber in crimped staple form will beimproved by the process of the present invention, particularly thosewhich have well-defined grooves and/or channels as shown. The brokenlines to the left of 2c are included to illustrate various alternativedesigns and/or additions to the basic design. The grooves could also bearranged in a circular pattern around a solid or hollow core. Thepreferred non-round fiber has at least 1 up to 30 or more grooves and/orchannels and/or legs which are substantially continuous. Fibers having aplurality of grooves have a larger surface area per unit weight thanround fibers and thus can be coated with more lubricant. Fibers havingat least one continuous cross-sectional groove preferably have at leastabout 0.3 wt. % lubricant coated on their surfaces whereas fibers havingfive or more grooves have at least about 0.5 wt. % lubricant coated ontheir surfaces.

A preferred fiber form useful in the process of the present invention isa tow of continuous filaments of between about 10,000 up to at least100,000 total denier. However, tows of much greater denier can be usedalso. This tow as with other tows (crimped or non-crimped) can beprocessed through a tow feeder after the tow dryer (skipping the cutter)and collected in a baler to form bales which are convenient forshipment. The tow subsequently can be opened or spread by rolls and/orjets and thereafter used in various nonwoven products, filters, etc. Forstaple fibers, the total tow denier can be as small as 30,000 and aslarge as at least 2,000,000. It is also preferred that the fiber of thepresent invention be subjected to crimping immediately after beingcontacted and spread with the heated solution of processing lubricant.The preferred crimped or non-crimped fiber has a staple length of about0.5 cm to about 15 cm and/or a denier per filament of about 0.7 to 200.

The process of the present invention preferably entails contacting agroup of fibers arranged in a relatively flat band (drawn or undrawntow) with at least one of certain processing lubricants at an elevatedtemperature; causing the processing lubricant to penetrate into the towto coat the fibers; subsequently subjecting the tow to pressure viadriven rolls followed by heating the tow at a temperature for a timesufficient to bake or dry said lubricant onto and/or into the surface ofthe fibers. The driven rolls can be the rolls of a crimper.

The treated fibers in the form of tow, crimped staple or uncrimpedstaple can be subsequently blended or combined with at least one othertow or staple fiber (such as a binder fiber); subjected to suitablenonwoven processing to form a web with the web being subsequently heatedand appropriately compressed to cause the blended fibers to compress andbond so as to produce a bonded, nonwoven material, such as a fabric orbatting.

A most preferred process of the present invention entails (1) subjectinga tow of caustic-treated and subsequently-neutralized polyester fibersas described to a heating device, most preferably rotating heated drumswith tow temperature controls and/or moisture sensors following an atleast partial removal of water after the neutralization step and anoptional application of at least one lubricant and/or additive; (2)forwarding the dried tow from the heating device at a tension suitablefor proper crimping; (3) applying at least one heated processinglubricant to the dried tow; (4) crimping the fibers or applying rotatingcompression rolls to the fibers (preferably immediately after applyinglubricant); and (5) heating the tow at a temperature for a timesufficient to bake or dry the lubricant onto and/or into the surface ofthe fibers.

The temperature range for the tow dryer is important with regard tomaintaining the desired crimp angle. For example, a tow of crimped fiberafter being dried in the tow dryer for 5 minutes at 75° C. could have awell-formed, relatively sharp average crimp angle of about 65 to 80degrees (by estimation method). However, this same fiber would havesuccessively wider, more open, more rounded, crimp angles, if it hadbeen dried at 135°, 50° and 175° C. for the same length of time.Assuming no change in hydrophilic lubricant, the increasingly more opencrimp angles create an increasing tendency toward reduced fibercohesiveness. Thus, the cohesiveness required for proper performance ofa given fiber in a particular nonwoven or textile operation must beconsidered and the temperature of the tow dryer is one of the factorswhich must be taken into account.

The fiber strength (tenacity), fiber elongation, percent shrinkage,etc., required for a particular product must be considered indetermining the temperatures and/or dwell times used before and/or afterthe crimper.

It has also been found that certain amounts of lubricant can be lostduring passage through the tow dryer and/or bonding oven depending upontemperature and time. Thus the amount of lubricant applied to the fibermust be sufficient to compensate for these losses and meet the targetlevel established for the final product, such as a bonded hydrophilicnonwoven.

Overall, it is clear that several factors must be considered inestablishing the operating temperatures and dwell times for a givenfiber. Applying lubricant (particularly the novel hydrophiliclubricants) in a heated condition prior to the crimper as describedprovides an extra margin of safety in terms of crimp formation,particularly with regard to crimp angle and apex formation.

Along with the appropriate crimp frequency, the lubricant composition, %lubricant, etc., it is most important to maintain an average crimp anglewhich provides sufficient fiber cohesion for at least satisfactoryprocessing during opening, blending, carding and subsequent operations.In addition, the crimp apex should be relatively "V-shaped" instead of"U-shaped" in order to produce crimp with greater permanence. Theprocessability characteristics of any fiber should make it possible,with a reasonable safety margin, to obtain the production rates anduniformity in opening, feeding, carding and other nonwoven or textileprocesses required for efficiency and profitability.

An overall cohesion value of any given sample can be quickly determinedby the cohesion-test method and instrument described in U.S. Pat. No.4,649,605 the disclosure of which is incorporated in its entirety hereinby reference.

This method determines whether or not crimped staple fibers eithernatural or man-made, have a weighted-average cohesion number of from 5.6to 12.5 inches (14.2 to 31.75 centimeters). This is done by initiatinggas impingement contacts at successively-increasing different pressurelevels against a carded web of staple fibers to cause in the carded webthe formation of visible bulges until at least 90% of the bulges areeventually ruptured for a particular pressure level. At such pressure,the ruptures form "tails" blown upward by the gas impingement whichequal or exceed the height of a failure-indicator bar or photocell. Thepressure and number of ruptures from each pressure level are recordedand a weighted average cohesion number is determined therefrom. Thestandard sliver weight used in this test is 65 grains per yard (4.59grams per meter) but the instrument can be calibrated using other sliverweights. The laboratory is maintained at approximately 55% relativehumidity at 75° F. (24° C.). The carding machine used for these testshad equipment and settings which made it possible to produce at leastgenerally acceptable card webs suitable for test purposes using fiberswith a wide denier-per-filament range of about 1.1 to 7.0 with staplelengths of about 1.25 to 2.0. The card was equipped with anautoleveller.

Cotton has relatively low cohesion compared to that which can beobtained with certain well-crimped and properly lubricated man-madefibers. Therefore, whenever possible, man-made fibers should belubricated and crimped so as to exceed the cohesion level of cotton to acertain extent in order to obtain high carding rates (in kilograms orpounds per hour) with at least satisfactory web and sliver uniformityand strength. In view of the history of cotton, the cohesion-testinstrument can be calibrated using a selected cotton to establish adesirable range of cohesion values (above those of the selected cotton).For example, cohesion tests of a blended sample from a properly-stored,aged bale of Memphis cotton with a Micronaire grade of 4.6 to 4.7(standard test for grading cotton) and an average staple length of 1 to1.063 inches (2.54 to 2.7 cm) produced cohesion values of about 5.1 to5.5 English (12.9 to 13.7 metric). A cohesion value is expressed innumerical terms to one decimal place without reference to the unit ofmeasure except to note that the scale is either on an English or metricbasis. Since it was known that this cotton was substantially typical incarding performance, the cohesion-test instrument was adjusted toprovide cohesion values at the lower end of the cohesion range. Thus,fibers with greater cohesiveness would be expected to provide cohesionvalues at least somewhat higher up the cohesion range of thatinstrument. As an alternative, properly-aged bales of stable syntheticstaple fibers with durable (relatively non-volatile) lubricants can betested and used to establish suitable cohesion values for comparisonagainst other fiber samples.

Tests for crimp frequency/angle and for % lubricant are important instarting and controlling the operation of a processing line but suchinformation does not determine the fitness-for-use of the fiber in termsof a comparative cohesion value. The cohesion value is helpful in thisregard by providing a measure of comparative strength of the card web ofone sample versus at least one other. In addition, the fiber mat fed tothe card and the carded web are examined to determine how well thefibers have been separated.

Favorable comparative cohesion values and normal carding performancewith excellent efficiency and production rates (kilograms or poundscarded per hour) can be obtained with our novel fibers, including themost-preferred caustic-treated non-round fibers produced by the novelprocesses and hot-lubricant-application jets shown in FIGS. 1, 4, and 6.

The determination of an approximate weight % lubricant on a fiber formineral-oil-based lubricants is made by the infrared test method viaanalysis of the extract washed from a sample of fiber. Infraredabsorption as described by Beer's Law is used to determine the mass oflubricant extracted into a suitable solvent, such as Freon (DuPontCorp.). The analyzer system dispenses solvent which washes the fiber toremove lubricant using a recirculating flow loop. The solution of Freonand lubricant is analyzed for total C--H bonds as it passes throughabsorption analyzer flow cell, such as a Wilks-Miran IR analyzer. Theresultant signal is converted electronically to be displayed as the %lubricant (by weight). Conversion factors can be used to enable a singleIR lubricant-test instrument to be used for analysis of severaldifferent lubricants which have been applied to various types of fibers.For example, a single testing station could be employed 1) to analyzepolyester fibers which have been lubricated appropriately for sewingthread, and 2) to subsequently analyze polyester fibers which receivedlubricant which is suitable for use in certain nonwoven products. An IRlubricant test instrument (the "Rothermel Finish Analyzer") can bepurchased from Lawson Hemphill Corp. of Spartanburg, S.C., USA.

Tube elution is the preferred method which can be used for determiningthe approximate weight % of hydrophilic lubricant such as the novellubricants on various fibers. In this procedure, a methanol extractionis utilized to try to remove substantially all lubricant components fromthe fiber, with a subsequent weighing to determine weight percentagelubricant. The tube elution method allows the determination of theamount of lubricant on a pre-weighed sample of fiber by extracting thelubricant with methyl alcohol from the fiber sample which has beenpacked into an open ended glass tube. The alcohol is caught in analuminum dish which is located on a steam bath. The alcohol isevaporated under controlled conditions, leaving the extracted lubricantas a residue. The weight of the residue is gravimetrically measured andthe percent lubricant is calculated. Appropriate safety precautions mustbe taken. These tests for weight % lubricant are generally adequate butdo have a certain amount of variability among laboratories, amongoperators, among repeat samples over time, etc. Thus, it seems that itis not possible to measure exact or precise amounts of lubricant on anyfiber. The process of the present invention provides fibers coated withat least one hydrophilic lubricant which provides improved overallperformance, particularly when used within certain weight % ranges oncertain fibers as described. The preferred minimum amounts of lubricantset forth in this specification should provide some margin for error inapplication and/or testing.

For the hydrophilic cellulose acetate fibers of Examples 6 and 7, anapproximate weight percent of the hydrophilic lubricant Was determinedsubstantially as described in ASTM Method D-2257-80 using diethyletherin a Sohxlet extraction procedure.

It is helpful to have an estimate of the differences in crimpcharacterizations such as crimp angle, crimp ratio, and crimp frequencyof staple fibers. Crimp affects the carding of the fiber and thesubsequent processing of the fiber into a nonwoven fabric. Staple crimpcan also affect the bulk, the hand and visual appearance of the finishedproduct. The available test methods for crimp characterization must beused with caution as will be described. Crimp characterizations areimportant in helping to establish good operating conditions for crimpersand tow dryers. Such characterizations can help detect majordifferences.

In this method of analyzing crimp, fiber chip specimens of staple fiberare placed on a black plush surface. The crimps along the entire fiberlength are counted. Both the relaxed (crimped) and extended fiberlengths are measured in inches or centimeters to one decimal place. Thecrimp angle and crimp ratio for each sample are then calculated.

Crimp is defined as the waviness of a fiber; a deformation of afilament, or group of filaments, in either the vertical or horizontalplane to the longitudinal axis of the fiber, which is of repetitivenature and is intentionally induced in the fibers by use of externalforces. Crimp level is defined as the number of angular peaks (crimps)per inch of extended fiber length, noted as crimps per unit length.Crimp ratio is defined as the direct ratio of the relaxed length ofcrimped fiber to the extended fiber length. A fiber chip is any group ofcrimped staple fibers (typically about 10 to 50) which remain inregister after being cut at the same time. Crimp angle is a calculatedvalue obtained from the following formula: ##EQU1##

It is important that the limitations of the crimp frequency and crimpangle tests be understood. Not only are the abilities of these tests topredict "fitness-for-use" not satisfactory, the reproducibility andrepresentativeness of practical samples sizes are not satisfactorilydependable. See ASTM Method D 3937 dated 1980 for the "Users andSignificance" section in which severe limitations of the test method forcrimp frequency are clearly stated. Also, see the "Applicable Documents"section in ASTM D 3937. This entire method is incorporated herein as areference.

When it is desirable to prepare the various novel fibers withoutsignificant crimp, the crimper rolls can be used essentially asforwarding rolls with no internal steam and with very low pressureapplied by the clapper. As an alternative, squeeze rolls followed byappropriate forwarding rolls ("star" rolls) can be located immediatelyafter the hot lubricant jets to replace the crimper.

The Automated Vertical Moisture Transport Test is one of the tests usedherein to measure the vertical liquid transport capability of thefibers. The fibers are either in original form or scoured by hot-waterjet as described and are placed inside a plastic tube. The tube is thenmounted vertically. This tube is subsequently brought into contact witha liquid. This test method is designed to automatically measure thefluid uptake of porous or fibrous specimens and to provide a profile ofthe fluid weight gain of the specimen with time. A fibrous specimencould be in the form of carded sliver or tow. In most applications ofinterest, the fluid is either water or artificial perspiration and thespontaneous movement of the fluid into the specimen provides aquantitative measure of the surface and capillary forces acting on thefluid in opposition to gravity. Once the specimen is prepared, (bytwisting the sliver one turn per 2.54 cm and inserting in a plastic tubeof about 7 mm inside diameter and cutting the ends of the sliver cleanlywhere they project from the 10.2 cm tube), mounted, and the fluid isplaced in contact with the bottom edge of the mounted specimen, thecomputer reads the balance (weight gain of the specimen) atpredetermined intervals of time. Preparation of artificial perspirationis described in AATCC Test Method 15-1979. A graph of this data is thenprinted as shown in FIG. 3.

As the number of suitable liquid transport grooves in the fiber isincreased, an increase in denier per filament tends to be needed tomaintain the cross-section, spinning performance, production rates, thedesired fiber quality and to avoid broken filaments, etc. It is possibleto obtain, through spinning and drawing combinations, fibers havingfinal deniers of approximately 5.0 to 200 per filament for the variousfibers with about 8 to at least about 20 grooves. However, it isrecognized that it could be possible to prepare a denier/filament lessthan 5.0.

When treating the preferred non-round fibers of the present inventionwith the hot processing lubricant solution it was unexpectedly foundthat excess liquid should be removed from the grooves of the fibersprior to contact with the hot solution containing processing lubricant.This is needed for fibers with 2 grooves but even more so for fiberswith 8 or more grooves so that the lubricant solution can then flow intothe grooves of the fibers. The location of this liquid removal methodcan be as illustrated in FIG. 1. Any method of effectively removing thisexcess liquid which is largely water can be considered to be usefulwithin this preferred process of the present invention. However, contactbars; squeeze rolls and air jets are preferred and a novel drying stepis most preferred as shown after 2a in FIG. 6. A criterion to be used tojudge the acceptability of an excess-liquid-removal system is whether ornot the desired percent of lubricant can be applied to the fibersatisfactorily after such excess liquid has been removed and the novelcontrolled drying step is most effective in this regard. Fibers withmore than about two grooves such as a fiber with eight grooves (FIG. 2d)carry so much liquid (dilute acetic-acid solution) forward to thecrimper that the lubricant from the jets essentially rides on thesurface of liquid and is not effectively deposited in the grooves to anyimportant degree. The crimper then squeezes the wet fiber causing mostof the hot lubricant and residual liquid (weak acetic-acid) solution tobe removed, leaving the fiber with a low lubricant level. A fiber witheight or more grooves (FIGS. 2c and 2d) has a critically greatercapacity to pick up acetic-acid solution than the "Figure 8" with twogrooves (FIG. 2a).

Two solutions to this residual liquid problem, with the second onerepresenting the more preferred solution, are as follows:

(I) At least one air jet, such as those disclosed in U.S. Pat. Nos.3,458,890 and 3,786,574, could be equipped with an appropriate hood;return drain; etc. and used following the bars and/or squeeze rolls onthe output side of the neutralization bath (located as shown at 1 inFIG. 1) to effectively reduce the level of residual solution on thefiber prior to reaching the hot-lubricant jets and/or other applicationmeans for hot lubricant application prior to the crimper.

(II) A most preferred versatile process permits the tow to besubstantually dried and/or baked following (1) neutralization, (2) anoptional additional washing treatment, (3) a liquid removal step (suchas bars and/or jets and/or squeeze rolls) and (4) an optionallubricant-application step. The fiber is then transported to receive thefinal application of hot lubricant prior to the crimper. See FIG. 6 fora drawing of this process which could effectively and efficiently applyhigh levels of the described lubricants to non round fibers which haveat least one groove.

Additionally, the novel hot-lubricant-jet (or jets) illustrated in FIG.6 can be used to apply lubricant(s) to tow in situations in which thecaustic treatment and subsequent neutralization steps are not used. Thisprocess can be operated in a variety of ways in order to subject theselected fiber to various operating conditions, temperatures, treatmentssurface coatings, two-step lubricant application, etc.

Fibers with many well-formed grooves can contain more lubricant thanthose with few such grooves. Fibers with many grooves such as 8 or morepreferably have at least about 0.3 wt. % lubricant coated thereon, morepreferably between about 0.5 and 2 wt. % of the novel lubricants appliedto the surfaces and grooves thereof.

Cross linking agents, such as epoxidized polyethers and polyglycidylethers with suitable initiators, etc., can be applied using the improvedprocesses to alter the surface characteristics of the fiber or to modifythe "hand" or feel, etc. The process shown in FIG. 6 providesconsiderable flexibility. For example, it is possible to convenientlyapply the selected cross-linking agent and any initiator which may beneeded at Jet (or Jets) 2A and subsequently apply a processing lubricantcontaining a minor amount of the cross-linking agent at Jet (or Jets)2B, etc. Such cross-linking agents can contain a minor amount ofultraviolet (UV) inhibitors, etc.

This improved process (illustrated in FIG. 6), has the capability toapply in a controlled manner, a variety of lubricants and othermaterials to the selected fibers and to provide the appropriate heattreatments. Thus, versatility is one of the major advantages of thisimproved process. As illustrated in FIG. 6, it is preferred to contactthe fibers with at least a portion of the lubricant or a component ofthe lubricant (e.g. a solution containing polyethylene glycol 600monolaurate alone) followed by heat-setting. This portion of thelubricant can be applied for example at 2A or between the 4th set ofrolls and the 2nd heat-setting unit. This application can then befollowed by contacting the fibers with heated lubricant at 2B. Forcrimped fibers this is all preferably conducted prior to the crimper.However (as a novel but much less preferred process) using the processillustrated in FIG. 1, at least one heated component of a lubricantand/or a cross-linking agent can be applied prior to the crimper; thetow is subsequently heat-set; and additional lubricant and/or othercomponents can be applied by a conventional spray booth or brushapplicator after the tow dryer.

Relatively undrawn polyester binder fibers and amorphous copolyesterbinder fibers, etc. can be rendered suitably hydrophilic by theapplication of at least 0.2% and most preferably at least 0.3 wt. % ofthe described heated processing lubricants by the process of the presentinvention. Binder fiber can be blended with at least one other fiber orother material, such as wood pulp, and the blend is then heated to causethe binder fiber to bond with the other component, usually in acompressed state, to make bonded non-woven hydrophilic products withvarious characteristics. A preferred copolyester binder fiber of about 2to 8 denier/filament with a 1.5 or 2 inch (about 4 cm) staple length canbe prepared from 100 mole % terephthalic acid, 69 mole % ethylene glycoland 31 mole % 1,4-cyclohexanedimethanol. However, other binder fibers,including bicomponent types, can be used. Examples of suitable binderfibers include "KODEL 44U" (undrawn polyester) and "KODEL 410"(copolyester) fibers made by Eastman Chemical Company and "CELBOND"sheath-core, proprietary bicomponent fiber made by Hoechst CelaneseCorp. The binder fibers can include side-by-side bicomponent types andthose made from polyolefins.

Rendering these fibers strongly hydrophilic provides a novel efficientmethod by which liquid-transport capability of the final products can beinitiated or enhanced. A significant improvement in crimp formation canalso be obtained if desired. In a typical application, these fibers areblended with at least one other fiber and subsequently bonded using heatand pressure. However, these novel hydrophilic copolyester binder fibersalso can be blended with wood pulp and/or other materials to createproducts with enhanced overall liquid-transport performance, includingdurability. When blended with wood pulp, etc., the copolyester isusually cut to short staple lengths of about 0.6 inches (1.5 cm) or lessand often contains relatively little or no crimp.

In recent years, the supply of viscose rayon has diminishedsignificantly. However, there are many excellent hydrophilic productscontaining this fiber which have been developed over the years, such asabsorbent products, cleaning fabrics, filters, multi-purpose nonwovens,etc. The novel fibers of the present invention could be used to extendthe supply of viscose rayon by making an appropriate blend.

It is believed that high-strength, high quality fibers such as thoseused in polyester sewing-thread could also be benefited by treatmentaccording to the process of the present invention.

The following examples are intended to further illustrate the inventionand are not intended as a limitation thereon.

EXAMPLES

Since fiber lubrication is not an "exact science", the identificationabove and in the following examples of a "poor" lubricant from theprocessability standpoint does not mean it will automatically cause atotal processing failure on all nonwoven and textile equipment in allsituations. However, it is believed that, overall, the poor lubricant,whether hydrophilic or otherwise, would cause significantly moreproblems, such as weak webs and/or sliver in carding, excessive webbreakdowns, holes in the webs and/or uneven (cloudy) webs, difficultyoperating consistently at the desired high rate of production,unsatisfactory opening of the staple prior to carding, etc. On the otherhand, a "good" lubricant does not automatically process well on allequipment at all times under all conditions. Perhaps, in a givensituation, the amount of this lubricant applied to the fiber might notbe satisfactory or the fiber crimp could be poorly formed or toovariable. There could be cases in which more of the lubricant isrequired in a particular process in order to perform well, etc. However,it is believed that, overall, this "good" lubricant would be morebroadly applicable to a larger number of nonwoven and/or textileprocesses and/or processing conditions with more favorable results thanthe "poor" one.

EXAMPLE 1

The following example illustrates some deficiencies of crimped staplefiber samples that are not prepared according to the present invention.A sample of fiber tow having a "Figure 8" cross section was prepared asfollows:

Dried fiber grade polyethylene terephthalate (PET) polymer of 0.63inherent viscosity (IV) was melt spun at about 293° C. through aspinnerette having 824 holes of dumbbell ("Figure 8") shape. IV is theinherent viscosity as measured at 25° C. at a polymer concentration of0.50 g/100 milliliters (Ml) in a suitable solvent such as a mixture of60 weight % phenol and 40 weight % tetrachloroethane. The spun fibers ofabout 4.4 denier per filament (dpf) were wound at 1250 meters perminute.

Two samples of this polyester fiber ("Figure 8" cross-section) wereprepared as drawn crimped staple with about 1.5 denier per filament and1.5-inch (3.8 cm) staple length using the process essentially as shownin FIG. 1 except without the application of the hot lubricant by the jetprior to the crimper. Approximately 0.15 weight % and 0.3 weight %lubricant was applied at room temperature by a spray method to the towafter the tow dryer.

The lubricant ("LUROL" 2617 from Goulston Co., Monroe, N.C.) consistedof methyl-capped POE (10) laurate as the major component and quaternaryamine carbonate as the minor component. The components were dispersed inwater to prepare a 15% emulsion. The necessary guides were used toprovide a path to and through the spraying booth and then to the cutterto cut the tow into staple. The weight % lubricant was measured by tubeelution as previously described.

The temperature of the first drafting bath with 2% sodium hydroxidesolution was maintained at about 69° C. An overall draw ratio of about3.3 was maintained during the drafting process. The heat-set unit wasmaintained at a temperature sufficient to produce a tow temperature ofabout 140° C. After the heat-set unit, the fiber was neutralized with aweak (at least about 0.4 to 0.6% by weight) solution of acetic acid inwater at about room temperature or above. Contact bars were mounted onthe downstream side of the neutralization bath in order to skim off amajor portion of the liquid. The fiber was crimped and then heat-set atabout 97° C. for about 5 minutes after crimping; was lubricated and thencut into about 1.5-inch (3.8 cm) staple. These samples were run on aResearch processing line using a total tow denier of about 50,000 to60,000. The tow had an average of 11 to 13 crimps per inch (about 5.1crimps per cm) with approximately a 90-to-100 degree average crimpangle. The crimps per unit length and the crimp angle were measured aspreviously described.

These two caustic-treated fiber samples had good liquid-transportcapability but had variable crimp with relatively wide (open) crimpangles and poor cohesion values. Carded webs from various samples ofthis fiber tended to be weak with some uneven webs and/or web failuresdue to low cohesion.

Cohesion values for these fibers were determined by the instrument andmethod disclosed in U.S. Pat. No. 4,649,605 as previously described. Thecohesion values for these fibers were low, averaging about 4.0 to 5.0.As previously indicated, the cohesion number is intended to be used toindicate comparative cohesion of staple fibers. The cohesion values aredetermined during carding and indicate comparative strengths of cardwebs representing the various samples.

EXAMPLE 2

The purpose of this example is to illustrate the liquid-transportperformance of fibers prepared using various aspects of the presentinvention when compared to noninventive aspects. A number of sampleswere prepared and tested for drop-wetting performance. The followingconditions were used in this study using a Research processing line andabout 55,000 total tow denier operated at a speed of about 40 meters perminute:

1. Polyester: Polyethylene terephthalate melt spun using the conditionsessentially as described in Example 1 with spinnerettes for round and"Figure 8" cross-sections.

2. Denier and staple length: about 1.5×1.45 inches (3.7 cm)

3. Fiber cross-sections: Round and "Figure 8" (One 180 kg creeling ofundrawn fiber was spun for each cross-section.)

4. Treatments: 2% caustic (C) followed by neutralization as describedabove and in U.S. Pat. No. 4,842,792 or no caustic (N).

5. Lubrication methods for the various samples: Two hot lubricant jets(HLJ) located above the tow, as shown in FIG. 4 placed within 30 inches(75 cm) of the crimper input using the process shown in FIG. 1;prior-art lubrication after crimping (LAC); or no lubricant (NL).

6. Lubricant target for all samples: 0.4+/-0.05 weight % using the samelubricant as used in Example 1.

7. Heat-setting treatment after crimping 145°+/-6° C. for approximately5.0 minutes with hot air circulation. Of course, the damp tow enteringthe dryer is not at this temperature for the entire time.

8. Drop-wetting test method: AATCC 39-1971.

9. Tow tensions after the tow dryer through the cutter for Samples A, B,D, F and G were maintained at the minimum that was consistent with goodoperation of the cutter. The minimum air flow necessary to transport thestaple from the cutter through the delivery system to the collectionsystem was used. Tow tensions for the Samples C and E (lubricated aftercrimping) were higher at the cutter than the other samples because itwas necessary to pass over the guides and rollers that guided the tow toand through the lubricant-spray booth prior to the cutter as shown inFIG. 1. It was not necessary for samples A, B, D, F and G to passthrough this booth.

10. Nonwoven fabric construction: about 16 grams/sq. yard (19.1 gramsper sq. meter) of carded fiber was powder-bonded with about 4 grams/sq.yard (4.8 grams per sq. meter) of Eastobond 252 polyester powder. Thebatting was created in two layers from two nonwoven carding machineslocated to deliver one layer on top of the other prior to thepowder-application machine with subsequent heating and passage throughbonding rolls to compress the material to form a thin sheet of bondednonwoven fiber. This powder-bonding method is well known in the nonwovenmanufacturing industry.

11. Scouring method: Hot-water jet as described above. The jet deliveredabout 1100 cubic centimeters of water per minute which had been heatedto about 54° C. with a pressure at the jet of 20 psig (138KPa)maintained at about 6 inches (15.2 centimeters) from the nonwovensamples (22.9×71.1 centimeters per sample) for 60 seconds.

Each sample of nonwoven fabric was tested for drop wetting in theoriginal form and after receiving a 60-second scour. The averagedrop-wetting results (in seconds) are as set out in Table 2.

                  TABLE 2                                                         ______________________________________                                                                     Drop Wetting Time***                                                          After Samples Were                               Cross-            HLJ/LAC    Scoured for:                                     Sample                                                                              Section  C/N    or NL    0 Sec   60 Sec                                 ______________________________________                                        A.    FIG. 8   C      HLJ      2.8     4.3 to 7**                             B.    FIG. 8   N      HLJ      2.8      48                                    C.    FIG. 8   C      LAC      6.2      82                                    D.    Round    C      HLJ      4.8     118                                    E.    Round    C      LAC      7.6     600                                    F.    Round    N      HLJ      11.8    600                                     G.*  FIG. 8   N      NL       600.0   600                                    ______________________________________                                         *A light water spray was necessary in order to process this unlubricated      fiber through carding. The carding performance of Sample G was very poor      and the resultant powderbonded fabric was not uniform. Sample G does          provide an indication of the large difference in the dropwetting              performance of unlubricated fiber compared to (1) nonround fiber (Sample      C); (2) on embodiment of the novel fibers (Sample A); and (3) the other       samples representing the various treatments shown above.                      **Multiple tests were run on the scoured samples for the more preferred       novel fiber.                                                                  ***It is recognized that there is a certain amount of variability in the      AATCC 391971 precedure caused by visual recognition and judgment of the       end point at which the drop has been fully dispersed. To reduce               variability, these tests were performed by one senior operator to make        comparisons among samples as accurate as possible. Other operators could      obtain differences in absolute time measurements due to the recognition       and judgment factors.                                                    

The results were plotted graphically as shown in FIG. 5 representing thewetting time in original condition and after scouring for 60 seconds.

The results for Sample F indicated that round cross-section fiberprocessed without caustic but with the hot-lubricant jets (to attempt toimprove crimp formation) had relatively poor liquid-transportdurability. Unexpectedly, the results for Sample B indicate that, evenwithout caustic, the hot-lubricant-jet process followed by crimping andheat-setting as previously described could be of benefit in preparingproducts for at least one-time use (nonwovens for cleaning applications,wipes, incontinence products, etc.). The tests on Sample G, which wasnot lubricated with a hydrophilic product, did not produce satisfactorydrop wetting results.

In view of these overall results, our inventive process with lesspreferred lubricants provided drop wetting at least equal to andpossibly somewhat better than the conventional processes.

EXAMPLE 3

Except for heat-setting at about 75° C. instead of about 145° C., fiberessentially identical to Sample A in Example 2 was prepared using twohot-lubricant jets located above the tow as shown in FIG. 4.Approximately 0.4 weight % lubricant was applied. This lubricantconsisted of 70 weight % polyethylene glycol 600 monolaurate and 30weight % polyoxyethylene (5) potassium lauryl phosphate prepared as 15 %emulsion in water. This sample had excellent wettability. However, whentested for cohesion during carding using the method previouslydescribed, the crimped staple sample had poor (low) cohesion and thusdid not provide an acceptably balanced overall performance.

EXAMPLE 4

Fiber-grade PET polymer of 0.64 IV was melt spun at 280° C. through a16-hole spinnerette to make filaments with "8-groove" cross-sectionssomewhat similar to that illustrated in FIG. 2d. The 40 denier perfilament fiber was spun at 1500 meters per minute and subsequently wasprocessed on a tow-processing line as shown in FIG. 1. The total towdenier was about 55,000.

About 400 pounds (182 Kg) of this eight-groove fiber were spun and woundonto tubes in the relatively undrawn state; placed in the creel on theResearch processing line; drafted with approximately 2-to-1 overall drawratio in a heated bath containing 2% caustic to obtain about 20-22denier per filament; processed through the steam chest and heat settingunit; immersed in the neutralization bath containing weak acetic acid(about 0.5%); and treated with two top hot-lubricant jets in series asshown in FIG. 4 prior to the crimper and tow dryer with the objective ofobtaining at least about 0.4 to at least about 2 % lubricant by weightdried onto the hydrolyzed fiber which was prepared in the form ofcrimped staple. See FIG. 1 for a drawing of this process. The lubricantwas the same type as was used in Example 3.

Except for the necessary change in draw ratio, the processing conditionswere similar to the ones used successfully on the "Figure 8" fiber asshown in the previous examples. However, the desired percent lubricantwas not obtained. Surprisingly, two separate tests indicated that thelubricant level was only about 0.03 to 0.1 weight % using the same tubeelution test that was used in the previous examples. After doubling theconcentration of the lubricant supply from 20 to 40 weight %, the fiberhad only about 0.19 wt. % which was far below the most preferred minimumapplication of at least 0.5 wt. % or more for fibers with about 8 ormore grooves. As the concentration of the lubricant supply was increasedto 40 wt. %, the lubricant became thicker and difficult to work with,even when heated, and proper penetration into the tow band becameincreasingly difficult to achieve.

Moreover, with the jets fully open, there was a large loss of lubricantwhich poured over the sides of the tow into the lubricant drain. Thecrimper-roll pressure was then reduced to allow more lubricant to becarried forward with the tow, however, crimp formation deteriorated andwas unacceptable.

We discovered that excessive liquid retention in the grooves was theproblem. This excessive liquid simply blocked the lubricant fromproperly entering the grooves. A novel process was then designed toovercome this problem as illustrated in FIG. 1 with at least one PartialLiquid Removal Means 1. In this case, in addition to the wiper bars thathad been used for the "Figure 8" samples, an air jet system wasinstalled after the bars to remove the excessive liquid after theneutralization bath and prior to the hot lubricant jets.

Using this novel process with a concentration of about 25 wt. % of thelubricant in solution, fibers with eight grooves were prepared with atleast 0.5 to 1.5 wt. % of the lubricant of Example 3 dried on in the towdryer as has been previously described. The fiber was found to behydrophilic.

EXAMPLE 5

Caustic-treated fiber similar to that made for Sample A in Example 2(except as stated below) was prepared using two hot-lubricant jetsoperated at about 80° C. located above the tow as shown in FIG. 4. Thecrimped tow was dried in the tow dryer at 65° C. for about 5 minutes.This example compares the fiber opening, carding performance, cohesionvalues and vertical-wicking performance of four hydrophilic lubricantsapplied by hot lubricant jets to 1.5 denier per filament, 1.5 inch,polyester fiber in a "Figure 8" cross-section. The fiber for all fourlubricants was produced on the same line in an effort to hold processingvariability to a minimum. The desired minimum weight % lubricant was atleast 0.3. The crimp frequency was approximately 14 to 16 crimps/inch.The approximate mean crimp angle of about 70 degrees was obtained usingthe estimation method described in Example 9. However, as previouslystated, crimp frequency and angle are useful rough estimates to have insetting up the operation of a processing line but are not sufficientlyreproducible for acceptance sampling and do not provide an adequateindication of carding performance.

The samples were treated as set forth in Table 3.

                                      TABLE 3                                     __________________________________________________________________________                      Wt. % Lubricant                                                  Lubricant    Test Performed On                                                                        Tested Later                                          Components   Crimped Staple                                                                           On                                               Sample                                                                             By Wt. %     Sample at the Cutter                                                                     Carded Sliver                                    __________________________________________________________________________    A    90 PEG 600 Monolaurate                                                                     0.36       0.47                                                                              0.48                                              10 Antistat*                                                             B    45 PEG 400 Monolaurate                                                                     0.42       0.52                                                                              0.56                                              45 PEG 600 Monolaurate                                                        10 Antistat*                                                             C    90 PEG 400 Monolaurate                                                                     0.39       0.47                                                                              0.46                                              10 Antistat*                                                             D    Lubricant same as                                                                          0.32       0.34                                                                              0.34                                              Example 1                                                                __________________________________________________________________________     *4-ethyl, 4cetyl, morpholinium ethosulfate                               

The samples were made on a single processing line using the same crimper(3/4" width rolls) adjusted by the same experienced operators. The testsfor % lubricant by weight (using tube elution) indicated that at least0.3 weight % had been applied to all samples by the two hot-lubricantjets (minimum had been met). The tests that were made on the crimpedstaple sampled at the cutter during processing indicated an overalltight grouping of results centering around an average of about 0.37weight %. However, when the carded sliver was tested later, it was foundthat, overall, Samples A, B and C had very good agreement as a group inaverage weight % lubricant but that Sample D was about 0.12 to 0.22weight % lower than A, B and C. Sample D did exceed our minimum targetof 0.3 wt. % in tests on both staple and sliver. Each sample was placedin a chute-feed system to be subsequently opened by tumbling, spikeapron, fine opener and air currents in the standard manner and thenautomatically fed to a textile carding machine which was equipped with acohesion test unit as described. The following results in Table 4 werereported by the Technical Service Laboratory personnel who conducted theevaluations:

                  TABLE 4                                                         ______________________________________                                                          Observation of                                                                             Comparative                                          Fiber Opening                                                                             Carded Web   Weighted-Average                               Sample                                                                              Performance For Strength Cohesion Value                                 ______________________________________                                        A     Good        Weak         4.6                                            B     Good        Normal       5.7                                            C     Not Satis-  Normal       6.4                                                  factory                                                                 D     Good        Normal       5.6                                            ______________________________________                                    

Overall, no advantage was found for Sample D over Sample B. The testsand observations were made by experienced carding operators who havemade many such tests on various types of polyester fibers over a numberof years. Thus, the results show that the lubricant formulation ofSample A provided good fiber opening but poor cohesion while theformulation for Sample C did not provide satisfactory fiber opening butdid provide good cohesion. The results further indicate that whencombined as was done for Sample B, the components provided good overallperformance as shown above. In addition, the results indicate that theproportions of the components of the lubricant used for Sample B couldbe varied to a certain extent to provide increased or decreasedresponses for different fibers and to satisfy different finalobjectives.

Carded sliver (65 grain) from each of the four samples was saved forevaluation by the Automated Vertical Moisture Transport Test previouslydescribed. Average capacity of each sample expressed as the weight ofliquid per gram of fiber (grams/gram) was as follows:

Sample A--4.9

Sample B--5.3

Sample C--5.3

Sample D--4.2

The results are shown in FIG. 3 and indicate that the novel 3-componentlubricant (Sample B) is least as effective in vertical transport as thelubricants used for Samples A, C and D and possibly slightly moreeffective in this regard. The unexpected results indicate that the novelthree component lubricant-antistat, particularly when applied in aheated condition by our novel jets, provides improved, well-balanced,overall performance and improved overall margin of safety in terms offiber opening, cohesion, and processability with at least equal andpossibly somewhat better hydrophilic performance compared to prior art.Additional versatility is indicated by favorable results obtained withdifferent cross-sections and fiber polymers. The preferred applicationmethod is by our novel hot lubricant jet process but other applicationmeans can be considered.

EXAMPLE 6

The purpose of this example is to illustrate the use of the presentinvention on fibers other than polyester. Using the well knownsolvent-spinning process (acetone), cellulose acetate fibers of 3.3denier per filament in a "Y-shaped" cross-section were spun frommultiple cabinets and then were guided across a lubricating roll andinto a crimper to form a 50,000 total denier crimped tow. This tow wasthen introduced under suitable low tension to the first set of rolls ofthe process shown in FIG. 1. The tow was passed through a draw bath atabout 60 degrees C. using a draw ratio of about 1.2 to 1. A portion ofthis drawing step was used to remove the original crimp to create a towwith little or no crimp for this experiment. The bath was equipped withLiquid Removal Means 1 on the output side and the tow subsequentlypassed through a steam chest and the heat setting unit both of whichwere maintained at about 100 degrees C. The bath and liquid-removalmeans were also used to remove at least the most easily accessibleportion of the spinning lubricant (mineral-oil based).

A hot-lubricant jet applied the most preferred and novel hydrophiliclubricant (heated to 80° C.) immediately prior to the 0.5-inch widthcrimper. The lubricant was composed of 49 wt. % PEG 400 monolaurate, 49wt. % PEG 600 monolaurate and 2 wt. % 4-ethyl, 4-cetyl, morpholiniumethosulfate at a 20 wt. % concentration in water. These are the samethree components used to prepare the lubricant for Sample B in Example 5but with the antistat reduced to 2 wt. % with a corresponding increasein the other two components to 49% each. Approximately 0.75 wt. % of thelubricant was applied to the fiber. The crimped tow was dried at about70° C. for about 5 minutes. The resultant staple had a relatively dryhand.

This test was intended to determine whether or not a relatively lowlevel (for cellulose acetate) of lubricant would be satisfactory for 1)processability on a nonwoven carding machine and 2) liquid-transportproperties. The lowest satisfactory tension for cutting a 2-inch staplelength was used. The staple was found to have about 12 to 14 averagecrimps per inch at about an 85 to 90 degree average crimp angle usingthe estimated method described in Example 9.

In a small-scale experiment, it was possible to card the fiber (on acarding machine for nonwovens) but there was a definite indication ofstatic at this weight % of the lubricant. Thus, it was clear that forproduction purposes, at least a higher level of the antistatic componentand perhaps the other components of the lubricant would be needed forcellulose acetate fiber.

The carded web was then subjected to a needle-punching operation inorder to create a nonwoven fabric which was suitable for testing. Theneedle-punched nonwoven weighed about 3.8 ounces per square yard with athickness of about 0.106 inches under a pressure of 0.01 pounds persquare inch. The fabric had good liquid-transport properties asindicated by basket-sink tests in distilled water. The averagebasket-sink time was 5.38 seconds obtained from the following individualtests: 7.65, 5.30 and 3.20 seconds.

The cellulose acetate samples described in this Example 6 created aspecial analysis problem due to the fact that mineral oil basedlubricant was applied during spinning and was only partially removed bythe drafting bath prior to application of heated hydrophilic lubricantas subsequently described. It was necessary to heat these samples for 16hours at about 100° C. in order to substantially remove the mineral oilbefore performing the tube elution procedure. The dried samples wereallowed to condition for about 8 hours to determine % moisture regainand were then dried at about 20° C. for about 30 minutes prior toperforming the tube elution procedure.

EXAMPLE 7

This example was conducted substantially according to Example 9 exceptthat the heat setting unit temperature set at about 140° C. and at leastabout 3 weight % of the lubricant of Example 6 was used:

The fiber was blended with 20 weight % Kodel 410 binder fiber andprocessed to form a bonded nonwoven fabric of about 40 g./sq. yd. Thisbonded fabric was found to contain about 1.5 wt. % of the lubricant.There was no indication of significant static. The bonded nonwovenfabric had an average drop-wettability of 1.3 seconds with a low valueof 0.6 and a high value of 2.8 seconds. An average wetting time of 1.2seconds was obtained in the basket sink test.

EXAMPLE 8

Fiber similar to Sample A in Example 2 was prepared using three hotlubricant jets as illustrated in FIG. 4. Approximately 0.4 to 0.5 weight% of the following lubricant was applied at a temperature of about 85degrees C.:

45 weight % PEG 400 monolaurate

45 weight % PEG 600 monolaurate

10 weight % 4-ethyl, 4-cetyl, morpholinium ethosulfate

The lubricated, crimped tow was heat-set at about 75° C. in the towdryer.

In order to properly seal off excess lubricant flow, it was helpful tocover the holes in the bottom jet which extended beyond the edges of thetow. These holes can be covered in any suitable manner, however,adjustable collars were used as shown in FIG. 4. Then at least onebottom jet was oriented as shown to prevent, as much as is practical,any dry contact between the jet surface and the tow. Preferably, thefiber-contact surfaces of the bottom jet are coated with a suitablelong-wearing material, such as a ceramic coating.

No problems were found in using the novel three-jet lubricationapparatus and method in this test. Excessive flow was provided to thebottom jet with a return of excess lubricant to the lubricant heatingand supply tank. Since three jets were not required to apply the targetlubricant level to this about 55,000 to 60,000 denier tow, the bottomjet was removed to continue the experimental work using the top twojets. The fiber was "Figure 8" polyester of about 1.5 denier perfilament by about 1.5 inch staple length. We concluded that the novelthree jet design shown in FIG. 4 would be of major benefit in applyingheated lubricant to the large tows of at least about 800,000 totaldenier up to several million total denier which are typical of fullscale production lines for polyester and other fibers.

EXAMPLE 9

This example is a further illustration of the overall performance of thethree component lubricant-antistat composition used in Sample B inExample 5. An "8-groove" polyester fiber drafted to about 5.9 denier perfilament and crimped following application by jet of about 0.6 to 0.9wt. % of this novel lubricant heated to about 80°-85° C. The analyses ofthe wt. % lubricant on the fiber were 0.58 and 0.94 and represent twodifferent tests conducted when the fiber was being run and then latersampled from storage. These results are further examples of variabilitythat we have found at times in repeat tests and also betweenlaboratories, etc.

The crimped fiber was heated in the tow dryer at about 66 degrees for 5minutes. The average crimp frequency was about 12 to 14 crimps per inchwith a crimp angle estimated to be about 69 degrees.

The estimation method for crimp angle involves comparing lengths ofcrimped tow to the lengths obtained after straightening the same tow andconverting the ratio of the lengths to an estimate of the average crimpangle.

The staple was cut to about 1.5 inches. It is important, particularlyfor non round fibers such as illustrated in FIGS. 2a, 2b, 2c and 2d tomaintain the lowest tow tension entering the cutter that is consistentwith satisfactory control of staple length in order to avoid excessiveincreases in crimp angle with a reduction in cohesion.

The textile carding machine used for this example was adjusted forrunning about 1.5 or less up to about 3.0 denier/filament with the mostsatisfactory carding performance for these general multi-purposesettings. However, this carding machine was equipped and set in such amanner that it was possible to run staple up to about 7.0denier/filament with at least acceptable web formation even though thisis outside that most satisfactory range. The 5.9 denier/filament fibersof this example were run on the same carding machine equipped with acohesion test instrument which was used for the other cohesion tests inorder to obtain a weighted-average cohesion value to compare against thevalues obtained in Example 5. With the denier/filament outside the mostsatisfactory range, some undesirable balled-up and tangled fibers wereproduced between the carding cylinder and the fixed flats of the cardingmachine. However, it was possible to produce an acceptable web fortesting and a cohesion value of 5.6 was obtained. The web was judged tohave at least adequate strength. Thus, the novel hot-lubricant-jetprocess and novel three component lubricant-antistat could be usedsatisfactorily for overall performance of the "8groove" fiber previouslydescribed. The carded sliver was found to be hydrophilic.

EXAMPLE 10

An "8-groove" polyester fiber was produced under the followingconditions:

    ______________________________________                                        Drafting bath temperature                                                                       About 72° C.                                         Liquid removal means                                                                            Contact bars and air jet                                    Steam tube temperature                                                                          About 185° C.                                        Caustic treatment None                                                        Neutralization treatment                                                                        None                                                        Heat-setting rolls                                                                              Not heated                                                  Crimper width     0.5 inches                                                  Tow-dryer temperature                                                                           About 130° C. (5 minutes)                            Total tow denier  About 55,000                                                Crimp per inch    About 12 to 14                                              Estimated crimp angle                                                                           All samples were estimated                                  by the tow-estimation                                                                           to be greater than 90°                               method:           with the samples lubri-                                                       cated by hot lubricant jet                                                    having somewhat sharper                                                       angles than spray-booth                                                       samples.                                                    Weight % lubricant applied*                                                   a.  PEG 880 sorbitan  0.49 by jet (about 80-85° C.)                        monolaurate                                                               b.  Same as a.        0.55 by spray (room                                                           temperature)                                            c.  PEG 880 sorbitan  0.47 by jet (about 80-85° C.)                        monostearate                                                              d.  Same as c.        0.49 by spray (room                                                           temperature)                                            Denier/filament   About 10 +/- 0.5                                            ("8 groove" fiber)                                                            Staple length     About 2 inches                                              ______________________________________                                         *Each lubricant consisted of 98 wt. % of the major ingredient plus 2 wt.      4ethyl, 4cetyl, morpholinium ethosulfate anistatic agent mixed as a 20 wt     % concentration in 80 wt. % water.                                       

These fibers were subsequently bonded using Kodel 410 binder fiber aspreviously described to form an approximately 40-gram per square yardbonded nonwoven in which the fibers are heated and compressed to formthe fabric in a manner well known in the art.

All four nonwovens were found to be hydrophilic in basket-sink anddrop-wetting tests. This process in which the two dryer was operated at130° C. was found to open two crimp angles significantly wider than theangles obtained in Example 5 in which hot-lubricant application of thepreferred lubricant formulations was used prior to crimping with the towdryer operated at less than about 85° C. See Example 5 for comparison inwhich the heat-setting rolls are heated and the tow dryer is operated ata temperature below about 85° C. The process illustrated in this Example10 is less preferred than the process illustrated in Example 5 but canbe used in those situations in which the resultant fiber is found toperform at least acceptably in the subsequent nonwoven and/or textileprocesses.

EXAMPLE 11

This example illustrates the application of the novel three-componentlubricant-antistat composition used in Example 7 in an effort to attemptto create a hydrophilic binder fiber. KODEL 410 binder fiber (previouslydescribed) was chosen. A relatively hydrophobic lubricant (mineral-oiltype) had been used satisfactorily on this fiber for a number of yearsfor various nonwoven applications.

About 0.25 weight % of the lubricant of Example 7 was applied to theKODEL 410 binder fiber (about 8 denier/filament) by a spray booth atroom temperature. Subsequently, this fiber was blended with a majorportion (about 80 wt. %) of an "8-groove" crimped staple. It was foundthat, during opening and feeding of the fiber, the binder fiber hadbecome brittle and broke into many small lengths. Laboratory testingrevealed that this fiber had lost a significant amount of strength and %elongation. Over a period of 50 days, the fiber became rapidly morebrittle and weaker with sharply reduced elongation and is therefore notsuited for this application as a binder fiber.

EXAMPLE 12

This example illustrates the application of the two novel lubricants ofExample 10 on separate samples and to attempt to provide a binder fiberwith improved hydrophilic action. The lubricants used in Example 10 wereapplied at about 0.25 wt. % to samples of tow used to make KODEL 410staple fiber. Over a period of 50 days, the tow samples had only slightlosses of strength and elongation. Thus, these two lubricants would besatisfactory to use in preparing binder fiber with hydrophilicproperties.

EXAMPLE 13

In an aging test of the novel three-component lubricant, hydrophilic,bonded nonwoven fabrics of Sample B in Example 5 and Example 7 werestored for over 7 months and were then examined. It was found that thebonded structure and hydrophilic function of these fabrics had beenretained.

We claim:
 1. A process for treating fibers comprising:(A) contactingfibers in a tow band with a free flowing solution containing about 5weight percent or more of a substantially non-tacky antistatichydrophilic lubricant at a temperature between about 40° C. and theboiling point of the solution; (B) spreading said solution into said towband to substantially coat all surfaces of said fibers; and (C) heatingsaid fibers at a temperature of about 40° C. or more for a sufficienttime to dry the lubricant-coated fiberswherein any excess liquid presenton the fibers has been removed prior to said contacting of step (A) andsaid tow band coated with said solution is crimped after said contactingof step (A) but prior to said heating of step (C).
 2. The processaccording to claim 1 wherein said lubricant comprises a major portion ofat least one compound selected from the group consisting ofpolyoxyethylene fatty acid esters, polyethylene glycol fatty acidesters, and fatty acid glycerides.
 3. The process according to claim 2wherein said lubricant also contains a minor portion of at least onecompound selected from antistatic agents and cross-linking agents. 4.The process according to claim 3 wherein said lubricant contains a minorportion of at least one antistatic agent selected from the groupconsisting of quaternary amine salts, salts of polyoxyethylene andorganic fatty alcohol esters, ethosulfate salts of quaternary ammoniumcompounds and acid salts of quaternary ammonium compounds.
 5. Theprocess according to claim 1 wherein said solution is an aqueoussolution containing about 10 wt. % or more of said lubricant and saidfibers are contacted therewith at a temperature between about 50° and100° C.; said spreading in Step B is produced by mechanical pressuremeans; and said heating in Step C is conducted at a temperature betweenabout 50° and 135° C. for at least 20 seconds.
 6. The process accordingto claim 1 wherein said fibers are selected from the group consisting ofpolyester, cellulose acetate, modacrylic, nylon, viscose rayon, andblends or mixtures thereof; have at least one axial groove; and are inthe form of a tow of at least 10,000 total denier.
 7. The processaccording to claim 1 wherein said fibers provided to Step A arecaustic-treated fibers that have between 2 and 30 axial grooves whichare substantially continuous and said fibers are contacted with saidsolution using at least one continuous flow means above said fibers andat least one continuous flow means below said fibers said continuousflow means positioned to avoid dry contact with said fibers.
 8. Theprocess according to claim 1 wherein said fibers provided to Step A arecaustic treated fibers that are substantially dry and have at least oneaxial groove.
 9. The process according to claim 1 wherein said fibersare non round hydrolyzed polyester fibers having a denier per filamentof about 0.8 to 200 and said lubricant is an aqueous solution containingat least 10 wt. % of a mixture of high and low molecular weightpolyethylene glycol fatty acid esters.
 10. The process according toclaim 9 wherein the low molecular weight polyethylene glycol fatty acidester is polyethylene glycol 400 monolaurate and the high molecularweight polyethylene glycol fatty acid ester is polyethylene glycol 600monolaurate.
 11. The process according to claim 1 wherein said lubricantcomprises at least one polyethylene glycol monolaurate or monostearatehaving a sorbitan group.
 12. The process according to claim 3 whereinsaid lubricant contains about 1 to 20 weight percent of an antistaticagent.
 13. A process for treating fibers comprising:(A) contactingfibers in a tow band with a free flowing solution containing about 5weight percent or more of a substantially non-tacky antistatichydrophilic lubricant containing a mixture of high and low molecularweight polyethylene glycol monolaurates at a temperature between about40° C. and the boiling point of the solution; (B) spreading saidsolution into said tow band to substantially coat all surfaces of saidfibers; and (C) heating said fibers at a temperature of about 40° C. ormore for a sufficient time to dry the lubricant-coated fibers.
 14. Theprocess according to claim 13 wherein said spreading of step (B) is doneby the driven rolls of a crimper and said fibers are crimped after saidspreading or step (B) and prior to said heating of step (C).
 15. Theprocess according to claim 13 wherein the low molecular weightpolyethylene glycol monolaurate is polyethylene glycol 400 monolaurateand the high molecular weight polyethylene glycol monolaurate ispolyethylene glycol 600 monolaurate.
 16. The process according to claim15 wherein said mixture contains at least 40 weight % polyethyleneglycol 400 monolaurate, at least 40 weight % polyethylene glycol 600monolaurate, and up to 20 weight % 4-ethyl, 4-cetyl, morpholiniumethosulfate.
 17. A process for treating fibers comprising:(A) contactingbinder fibers in a tow band with a free flowing solution containingabout 5 weight percent or more of a substantially non-tacky antistatichydrophilic lubricant selected from the group consisting of polyethyleneglycol sorbitan monolaurate and polyethylene glycol sorbitanmonostearate at a temperature between about 40° C. and the boiling pointof the solution; (B) spreading said solution into said tow band tosubstantially coat all surfaces of said binder fibers; and (C) heatingsaid binder fibers at a temperature of about 40° C. or more for asufficient time to dry the lubricant-coated fibers.
 18. The processaccording to claim 17 wherein said binder fibers are crimped after saidcontacting of step (A) and prior to said heating of step (C).
 19. Theprocess according to claim 17 wherein said lubricant contains a minorportion of an antistatic agent and a major portion of a lubricantselected from polyethylene glycol 880 sorbitan monolaurate, polyethyleneglycol 880 sorbitan monostearate and mixtures thereof.